1. Field of Invention
The present invention relates to optical processing systems and electrooptic spatial light modulators. More specifically, the present invention relates to near bandgap radiation based spatial light modulators using multiple quantum wells.
2. Background Art
Several types of spatial light modulators are now commercially available. A spatial light modulator (SLM) is an optical device which modulates an illuminating readout beam in at least one spatial dimension. Currently available SLMs suffer from one or more deficiencies in terms of their performance or practical usage. In particular, relatively fast response modulators such as General Electric's Oil Film Device or Sodern's KDP-based modulator have relatively low optical resolution and require large driving systems. Typically, electrical circuitry is used to drive and activate an optical modulator which, in turn, modulates an illuminating readout beam. The low resolution of these high speed spatial light modulators is due to a CRT or other high voltage adressing means and their write-in mechanisms.
Another class of spatial light modulators includes liquid crystal light valves (LCLVs). LCLVs do not require large driving systems and have high optical resolution. LCLV SLMs typically have semiconductor drivers for suitably driving the liquid crystal optical modulator. One commercially available LCLV SLM is the Hughes Aircraft CdS-based photoactivated liquid crystal light valve. Two other LCLV SLMs have been developed using either photoactivated Silicon or electronically addressed charge coupled device write-in mechanisms. Both of these SLMs demonstrate very high performance in terms of high optical resolution and dynamic range, but have relatively slow response which limits two dimensional frame rates to 100 Hz. Another disadvantage of these LCLV SLMs is their inability to operate at low temperatures, for example below 273 degrees kelvin. Satisfactory low temperature operation is required for some applications, such as infrared to visible image conversion used in certain optical processing systems. These two LCLV SLMs are now briefly described as background information.